In one corner, we have the most famous Hoya R72 filter. Against it, I have two cheaper filters from ebay. But how do they compare?

To start with I will show some findings on the Sony A350 under less than ideal conditions. 2nd part will be the modified Canon 300D in real world conditions. Finally I will also add some results from the Canon 50D for completeness. Why test all 3 cameras? The sensors may be sensitive to different wavelengths of IR, so the filters may give different results.

Onto the filters, here we show them in their cases.

On the left is an unbranded one. This was bought from ebay seller link-delight-uk and costs £12 delivered.
Needing no introduction, in the middle is the Hoya R72. A current good price is over £35.
On the right is a Pixco branded filter, bought from ebay seller cam.plus for just under £12 delivered. The case has a link to RocksPhoto.

The filters look much like each other on the outside.

Sony A350, Zeiss 16-80

These pics were taken getting late on a sunny day. The sun is somewhere behind the direction of shooting. Image is unprocessed camera jpeg output other than resizing.

Hoya R72 filter. 1s, f/4.5, ISO400

Unbranded filter. 1s, f/4.5, ISO400

Pixco filter. 1/4s, f/4.5, ISO400. 1st histogram is for the image as shown. Right histogram was the result when it was exposed the same as the previous filters at 1s.

Comparing the Hoya and unbranded filter, there is little difference between them. The unbranded filter is slightly brighter. Important note here is that for both of these, the leaves on the trees are relatively bright.

Comparing those two with the Pixco is another story. The Pixco stimulates the red channel significantly more. Just to get the overall histogram similar, I had to use a quarter of the exposure time. But in this case, note the leaves are relatively dark. When I first received these, by eye, the view through the Pixco was noticeably brighter. The question is, is the Pixco useful as an IR filter? Not in this condition. I will revisit it later.

Modified Canon 300D with IR block filter removed

Blind handheld shots so the area isn't exactly the same on each. A normal shot with the sun nowhere near in frame.

No filter. 1/200s, f/16, ISO100

Hoya filter. 1/200s, f/16, ISO100

Unbranded filter. 1/200s, f/16, ISO100

Pixco filter. 1/200s, f/16, ISO100

All these three look pretty much the same to me, even the Pixco filter which was different on the Sony.

Following is another set of shots. This time I was checking if the filters have any different flare characteristics. The sun was out of shot at the top of the frame.

No filter. 1/200s, f/16, ISO100

Hoya filter. 1/200s, f/16, ISO100

Unbranded filter. 1/200s, f/16, ISO100

Pixco filter. 1/200s, f/16, ISO100

Again, they all look the same to me. The filters don't appear to introduce any flare.

Time for the final update. Tests were done on the 50D with the 50mm f/1.8 II lens. Live view was usable for focusing, even if the 50/1.8 isn't the best for that...

Hoya R72 filter. 2s, f/8, ISO1600

Unbranded filter. 1s, f/8, ISO1600

Pixco filter. 1/4s, f/8, ISO1600

Do note all three use different exposures. The unbranded gave slightly more red channel output than the Hoya R72 so I had to knock it back a bit to stop clipping. As before, the Pixco gave a LOT more on the red channel.

Conclusions

So taking all the above what can we say?

Taking the Hoya R72 as the reference, the unbranded filter gave a very close result. Without doing a full spectral measurement on them, I'd hazard a guess it may be slightly softer in visible filtering characteristic, but on all cameras the result is close enough to the Hoya that the price really swings it.

The Pixco is much more different from the other two. On the modified 300D it behaved practically the same. On the unmodified cameras it looks more like a dark red filter and doesn't give that IR glow on vegetation. Yet looking through it by human eye, it does. My best guess on the reason is that this filter is letting through significantly more visible red than the other filters. On the IR modified camera, there was enough IR passing through to swamp the visible red. But on the unmodified cameras, the IR cut filters take out more IR such that visible red dominates.

Overall, the unbranded filter takes the win. Performance is almost the same as the much more expensive Hoya R72. Downside being unbranded is it may be hard to make sure you get this exact filter when buying. The Hoya R72 remains a safe choice if you have the money. I'd suggest avoiding the Pixco branded filter as it doesn't deliver on unmodified cameras.

The above examples were more to show the differences in filter response. On my IR camera, I set custom white balance so that clouds are white. This still leaves a generally red tint, and with a red-blue channel swap gives the commonest style of false colour IR images with blue sky white-ish everything else. The Canon 300D I used seems to be a little different in response though with man made blues e.g. (plastics, paints) coming out very blue still.